If you really wanted to do a "DIY" type deal you could use PVC pipe. Get some 2" PVC, cut it about 4' long. Heat one end with a torch and crimp it, but still allow holes for the water to drain. Tie a rope to the other end. Throw it in the water during spawning season. It may take a couple weeks to be effective because they like it all scummed up and nasty. We've had lots of success with them before. Its not uncommon to have 6 or 7 catfish in one. The bigger the pipe the bigger the fish in it typically so you can control what size you are getting.
ETA: No bait needed. But only effective during the spawn. Basically you end up with a lot of females with eggs.
This post was edited on 2/4 at 1:11 pm